R3R FRAME CHANGES

And the two values yet to find are the center of gravity location with the rider aboard and the gross weight. Then acceleration values can be used to calculate load transfer and anti-squat. And then you need to know the exact tire profiles so that you can calculate contact patch line deviation from theoretical centerline at various lean angles. Knowing all this you might begin to understand steering dynamics. Oh, and you need to know tire slip angles as well.

Actually, these dynamics are transient so any calculation is only an approximation at a given moment in time. Suspensions compress, center of gravity moves, trail changes, and anti-squat geometry varies with rear suspension travel. All these values change constantly as the bike is ridden around a curve. No given set of calculations tells the whole story of how the bike performs or how it feels. But, you will understand the system better for having performed the calculations.

One more point to ponder: Can a unicycle rider traverse a curve? How?

I'll bite -
Of course it can, we have all seen this done.
I would say that since the uni is one wheel and has no lean angle, the rider must rotate it about its axis by applying additional force to the outside pedal.
This would enable it to negotiate a curve in a series of chords and not a true radius.
 
Hmm ok now I've gone and confused myself lmao.

Plugging stock numbers of
32 degrees
2" offset
26.45" diameter
0 triple rake

RB Racing Rake and Trail Calculator
is 5.9" trail, seems close enough.
Really want my Forks back now just to redo measurements and make sure they're right.

Here are your given OEM dims calcs:

OEM Trig.jpg
Remember, these are OEM dims with a 150/80R17 - not a 140/75R17.
 
Those are the actual numbers I measured on my bike in the garage. The 2" offset I'll have to re-check. I am a bit suspicious of that number myself. EDIT: Assuming offset I'm getting right, being center of steering stem plane to center of axle plane as they run diagonally through the top of the stem and fork, then I re-measured a 2 inch offset.

Rear axle to swingarm I took just the other day, just measured center of pivot to center of axle, used a level running through midpoint of the swing arm pivot and a 90 angle to measure the distance between that plane and the vertical line through the rear axle. Some trig later, 13.2 degrees is the swing angle, a little steep, but, generally fantastic for a sporting feeling and is actually consistent with the behavior I've noticed. Shallow angles push wide on power a lot, steeper grip and go without excessive widening of the steering radius, or slip spin and drift smoothly. Mufasa does the later, either drives beautifully out of turns or slips and spins predictably.

As soon as the forks go back on later this week (I hope), I'll carefully double check all the dimensions again, to make sure.

Remember, as the shocks get longer, wheel base gets shorter and swingarm angle gets steeper. It's a combined effect I think of both more preload and more length on the back that causes such a drastic change in measured geometry.

When I say my bike is "flickable" it's an understatement, its downright ****ing agile. If you follow me around while were puttering about slowly, you'll see me oversteer turns a lot and have to correct wider, the bike just falls into turns, just like my Daytona does. In that thread I warned against people following my route of changes, 1" taller + high spring rates + the tire size changes really puts the bike into what some would call "scary" territory.

In fact, when we were out with Mike you may have noticed it, I distinctly remember having to correct wider a number of times.

At some point I'll have to toss you the keys so you can go evaluate for yourself :)

If I understand correctly, you are running the 240/55 and 140/75, same as I?
Your shocks are 1" longer, which indeed does very slightly shorten the wheelbase.
It also decreases your rake almost one degree & your trail by a quarter inch from mine.
So yours is indeed more "flickable" than mine . . . . . & perhaps even faster?!?!?!? :eek: :rolleyes: :roll: :thumbsup:
 
Oh but a unicycle does have a lean angle. The center of gravity always comes into play in any movement in any direction. At slow speed it only appears as if there is none. At speed, say like that of a motorcycle, the cycle and rider's CG would shift inward to offset the centripetal force generated. This would be like a motorcycle rider doing a wheelie in a curve.

The point is to question how a single wheel vehicle can be steered around a curve. No front wheel is required at all. There are acceleration and lateral forces involved, yet the wheel contact patch centerline is tangent to the curve radius.
 
Oh but a unicycle does have a lean angle. The center of gravity always comes into play in any movement in any direction. At slow speed it only appears as if there is none. At speed, say like that of a motorcycle, the cycle and rider's CG would shift inward to offset the centripetal force generated. This would be like a motorcycle rider doing a wheelie in a curve.

The point is to question how a single wheel vehicle can be steered around a curve. No front wheel is required at all. There are acceleration and lateral forces involved, yet the wheel contact patch centerline is tangent to the curve radius.

AT SPEED???
I've never seen a uni-cycle ride at any speed above slowly.
 
o_OOk all you Rocket brains, you are leaving me behind, but I do have one question, would it hurt anything to go with a 11.5 inch nitrogen shock to lower the bike an inch. Thanks
 
o_OOk all you Rocket brains, you are leaving me behind, but I do have one question, would it hurt anything to go with a 11.5 inch nitrogen shock to lower the bike an inch. Thanks

YES!!!
1) It will greatly reduce your lean angle, forcing you to ride like on a HD! :thumbsdown:
2) It will likely rub through your rear end wiring under the fender.
3) It will reduce your available suspension travel.
4) If you do something about the wiring and ride only like a granny, you may be satisfied.
I tried this years ago, very early in my R3R adventure. Got rid of them after a couple hundred miles.
 
Caveat: I slept in a Holiday Inn once.

That said, and it's not necessarily inexpensive . . . the Rocket is already about as friendly as they come in terms of putting one's feet down. If more is needed, a smaller front tire will get you part the way there, and a custom (read lowered) seat could get you the rest of the way. In the bargain, you'd likely have a better handling bike, and a more comfortable seat.

Just 2¢
 
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I find the Rocket seat is very wide at the tank. :thumbsdown:
At a 29.5 inch seat height, tis difficult to back up with 29 inch inseam legs! :thumbsdown:
I do run the 140/75R17 front & the 240/55R16 rear, which actually raises the seat height a quarter inch.
I also run beads which adds another quarter inch or so.
Handling performance is paramount to me, so I live with it, taking care of where I park.
 
I find the Rocket seat is very wide at the tank. :thumbsdown:
At a 29.5 inch seat height, tis difficult to back up with 29 inch inseam legs! :thumbsdown:
I do run the 140/75R17 front & the 240/55R16 rear, which actually raises the seat height a quarter inch.
I also run beads which adds another quarter inch or so.
Handling performance is paramount to me, so I live with it, taking care of where I park.
I have a Corbin seat on, and with a 30 inseam, I also noticed a little wide a the front. But nothing I can't live with,thanks for the info.
 
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